This application is for funds to buy a Zeiss LSM510 confocal microscope to replace a heavily used 9-year old LSM410, the main workhorse of the Vanderbilt University Cell Imaging Shared Resource (CISR) Currently, the CISR provides service to more than 150 VUMC laboratories, 72 laboratories use the LSM410 to support their research, most PHS-funded, to the extent of >2300 hours per year, trained users can access the facility 24 hours/day, 7 days a week The CISR has a history of excellent service, reliability and minimal down time In addition to the vital requirement for uninterrupted service, there is an increasing demand for modern live specimen imaging using advanced techniques, e g, FRAP, FLIP, FRET, rapid sequential line scanning (multi-tracking), and other capabilities not supported by our LSM410 The recent acquisition of an LSM510 system to support advanced applications of five major user groups has enabled increases in new users, total confocal imaging time, and feasibility studies for new investigators and new applications In spite of the additional system, the use of the LSM410 has increased and the time available to non-major user groups on the LSM510 is being rapidly absorbed from researchers unable to use the LSM410 due to its lack of functionality for new applications Significant disruptions and delays in confocal microscope-dependent research are anticipated within the next 1-2 years in lieu of replacement of the LSM410 with a new system These expectations are based on a projected increase in demand and a dwindling supply of key replacement components to sustain uninterrupted service Recent experience with obtaining critical spare parts available only from surplus, rebuilt or salvaged components support these expectations This application is a proactive step to prevent a disaster in delayed and lost NIH-funded research due to the inevitable decay of a heavily used instrument and to increase the quality and quantity of confocal microscope data.